Six Forgotten Warriors Chapter 4: The Six Fight Again - S5-E5
Audio problem: When Dr. Groitzig is saying "It's been so many years," he has his fingers in his mouth. While it's possible to speak with fingers in your mouth, your voice will sound quite different when doing so, and Groitzig's voice sounds normal.
Six Forgotten Warriors Chapter 2: Unclaimed Legacy - S5-E3
Other mistake: When Silver Sable infiltrates Kingpin's Russian lair with sleeping gas, before falling unconscious, Kingpin correctly deduces that he has been betrayed. In the next scene, Kingpin asks Silver Sable how she was able to infiltrate his lair, and she tells him one of his men is a traitor, which elicits an incredulous reaction from Kingpin, completely contradicting the previous scene where Kingpin already surmised there was a traitor.
The Wedding - S5-E1
Other mistake: When J. Jonah Jameson is on the phone with Wilson Fisk, one shot shows that the area of Jameson's desk between the receiver and the cord is colored the same gray color as the cord, instead of the golden-brown color the rest of the desk is.
The Wedding - S5-E1
Audio problem: When J. Jonah Jameson is telling Peter he can work off his wedding gift over the next decade or two, his mouth movement is slightly out of sync with the dialogue.
Six Forgotten Warriors Chapter 4: The Six Fight Again - S5-E5
Other mistake: The news footage of the elderly Six American Heroes being attacked by the Insidious Six is merely clips from the previous episode.
Six Forgotten Warriors Chapter 3: Secrets of the Six - S5-E4
Audio problem: When Kingpin is asking Scorpion if he is the traitor, his mouth movement is not in sync with the dialogue.
The Wedding - S5-E1
Revealing mistake: After Scorpion causes the chandelier to fall onto Spider-Man, the camera pans to the right and Scorpion appears out of thin air onto the screen.
The Wedding - S5-E1
Audio problem: When the orderly is telling Harry that he has visitors, his mouth isn't moving.
Secret Wars, Chapter 3: Doom - S5-E11
Other mistake: This series is in the same continuity as the other Marvel animated series from around the same time - X-Men, The Incredible Hulk, Iron Man, and Fantastic Four - by virtue of each aforementioned show crossing over with at least one of the others. However, in Fantastic Four, Dr. Doom had a German accent, and in this episode he has a Russian accent.
Spider Wars, Chapter 1: I Really, Really Hate Clones - S5-E12
Character mistake: When the group of Spider-Men are breaking into the Kingpin's building through the front door, Octo-Spidey uses a laser to cut a circle in the door and then proceeds to tear the door off its hinges with his robotic arms. Since he was just able to simply tear the door off, there was no need for him to cut the hole in the door in the first place. It's not like he needed to reach through the hole with one of the arms to unlock it from the other side.
Spider Wars, Chapter 2: Farewell Spider-Man - S5-E13
Character mistake: When Stan Lee is asking Spider-Man what he plans to do after saving all of reality, he responds by saying to find the real Mary Jane. Moments later in the final scene, Madame Web tells Spider-Man that she is taking him to find the real Mary Jane, which elicits an incredulous response from Spider-Man, as if he didn't know that was already the plan.
Suggested correction: It was a part of the character's redesign. The writer of Spider-Man, John Semper Jr, disliked the Fantastic Four cartoon to the point that he not only changed characters' designs but their voice actors as well.
Redesigning the character is not a valid correction, because it still creates a contradiction within the shared universe. Even under the pretense of redesigning the character due to not liking the previously established version, it would still be a deliberate mistake.
Phaneron ★